Open on the Emmys, September 2002: ”West Wing” executive producer Aaron Sorkin is collecting his third trophy for best drama, while ”Bernie Mac Show” creator Larry Wilmore wins his first-ever Emmy for writing the Fox comedy. Cut to the present: Wilmore is out of a job as executive producer of ”Mac,” and Sorkin’s ”Wing” tenure is tenuous at best.

Moral: Being the creator of an acclaimed TV show doesn’t guarantee job security. Sources say Warner Bros. Television (owned by EW parent AOL Time Warner) recently put Sorkin on notice, warning that it would no longer tolerate cost overruns on ”Wing” (due in part to Sorkin’s habit of delivering scripts late). Sorkin’s status sure isn’t bolstered by ratings – the show’s had an astonishing 20 percent drop in viewers – or critics (Too many characters! Drawn-out plotlines!). Despite industry speculation that ”Wing” may undergo an administration change, a Warner rep says that Sorkin currently remains on ”Wing” and is under contract with the studio for one more season.

Fox, meanwhile, is hunting for a new big cheese for ”Mac” after giving Wilmore his walking papers smack-dab in the middle of the show’s second season. The network and sister studio 20th Century Fox Television wanted to ditch him early in season 1, an insider says, when Wilmore wouldn’t follow such basic sitcom rules as using secondary story lines (he would often focus on one topic per episode). He also opposed taping before a live audience and favored provocative dialogue like the now-famous Mac-ism ”I’m going to bust your head ‘til the white meat shows,” which Fox feared would offend viewers.

But the last thing Wilmore (who cocreated ”The PJs”) wanted was a conventional sitcom. ”From Larry’s point of view, he’d say, ‘I’m doing something different, I don’t want to conform to traditional storytelling,”’ says a source close to the show. ”From the network’s point of view, that would be fine, if it were funny. But it wasn’t.”

Compared with last season, the show has dropped 17 percent in the 18-49 demographic and 13 percent in total viewers. Granted, Fox didn’t help by running it opposite ABC’s surprise hit ”My Wife and Kids” last fall.

Some industry vets believe that replacing a show’s visionary leader is a dangerous proposition. ”It’s the beginning of the end,” says one high-level TV exec. ”’ER’ stayed great because John Wells stayed. It’s the same with ‘Will & Grace’ and ‘Everybody Loves Raymond’ – the creators stayed.”

There are rare occasions when such a change proves successful: In its first season, ”Roseanne” creator Matt Williams was fired by the show’s hot-tempered star. ”No one’s irreplaceable,” says Williams, who went on to create ”Home Improvement.” ”People at home don’t have any idea who’s writing the story. If a show is firmly established, other people can come in and write it.”

Though Bernie Mac originally supported Wilmore’s goal of breaking the sitcom formula, the actor didn’t stand in Fox’s way, the source says. ”I’m confident that whoever steps in [Wilmore’s] shoes will be as unique and distinct as Larry,” Mac said in a statement. Wilmore has already rebounded, landing a development deal with NBC. Still, says a colleague, ”He was hurt.” Now the question is whether ”Bernie Mac” will be too.